1. Priority Claim
This application claims the benefit of priority from European Patent Application 09015443.6, filed Dec. 14, 2009, which is incorporated by reference.
2. Technical Field
The present invention relates to a display device with a liquid crystal display and a backlight.
3. Related Art
Liquid crystal displays have found broad deployment in various technology applications such as personal computers, multimedia equipment, mobile phones, etc. Liquid crystal displays (LCD) have also been successfully employed in navigation and/or entertainment systems for transportation means such as aircrafts, trains, or vehicles such as vehicles or autobuses. Nowadays, vehicles may have a plurality of information and entertainment devices on board for distributing various image display signals to the driver and, in addition, to the other passengers. This is accomplished by separate displays each capable of displaying a different image signal. For instance, a first display device may be provided for the driver and a second or additional device may be provided for the other passengers. As the driver needs to concentrate on the surrounding traffic flow, the driver's display may only provide essential information whereas the passengers' displays may also reproduce image details. Such displays may also be used for the display of video images or other control information of any vehicle information and entertainment device, such like a television or radio receiver, a digital video disc (DVD) player, a cell phone, an Internet access device, vehicle control devices, a vehicle rearview device, etc.
The displays provided for vehicle navigation, communication, and entertainment systems may require higher temperature resilience and mechanical load capacity through vibration. Moreover, because of the possibly changing light conditions in a vehicle, the liquid crystal displays may be provided with a suitable backlight and capable of reproducing a high contrast.
Backlight may be necessary for the liquid crystal displays to increase readability in low light conditions. For instance, in computer monitors cold cathode fluorescent lamps are typically employed in combination with a diffuser. Advances in production of light-emitting diodes (LED), which is a point source of light, enable employment of LEDs as a backlight, especially in smaller LCD screens such as screens of mobile phones. White or red, green, blue (RGB) have also been employed as a backlight for computer screens. For the picture quality of liquid crystal displays, the uniformity of backlighting plays an important role. Therefore, in order to provide an even backlighting, diffusers are used, which is typically a layer of plastic that diffuses the light emitted by the light source(s). However, especially when light-emitting elements generating heat such as LEDs are employed, the heat generated by the LEDs, when not appropriately dissipated, may raise the temperature within the housing and may reduce the quality and the lifetime of such a display device.
Mounting displays into a target location such as a dashboard of a vehicle may be problematic. The active area of the display may be partially covered by other mechanical parts of the display device such as diverse frames and housings if the display device is improperly mounted. Accurate positioning may be more difficult when more mechanical elements are used in the display device. Even if the tolerances (uncertainty in the position) of each mechanical element involved are small, the chain of tolerances caused by the sum of these uncertainties of each mechanical element and may result in imprecise positioning of the liquid crystal display screen with respect to the target location.
Providing displays for vehicle applications such as personal vehicles may also be challenging due to the high requirements on electromagnetic compatibility. Nowadays many electronic devices, including several antennas covering different frequency bands, measurement and control electronic, etc. are mounted on the board of a vehicle. This simultaneous function of a multiple electronic devices in such a limited space may also be problematic.
Therefore, a need exists for a display device with a LCD display and backlight arrangement that may reduce the adverse effects of heat generated from the backlight on the LCD display. In addition, a need exists for a display device with a LCD display and backlight arrangement that may reduce the tolerance chains of components for more precise assembling of the display device and positioning at a target location, as well as reduce the electromagnetism of the display device.